diff --git a/google/api_core/retry.py b/google/api_core/retry.py
index 44cd7469..bd3a4a65 100644
--- a/google/api_core/retry.py
+++ b/google/api_core/retry.py
@@ -114,9 +114,9 @@ def if_exception_type_predicate(exception):
 - :class:`google.api_core.exceptions.TooManyRequests` - HTTP 429
 - :class:`google.api_core.exceptions.ServiceUnavailable` - HTTP 503
 - :class:`requests.exceptions.ConnectionError`
-- :class:`requests.exceptions.ChunkedEncodingError` - The server declared 
+- :class:`requests.exceptions.ChunkedEncodingError` - The server declared
     chunked encoding but sent an invalid chunk.
-- :class:`google.auth.exceptions.TransportError` - Used to indicate an 
+- :class:`google.auth.exceptions.TransportError` - Used to indicate an
     error occurred during an HTTP request.
 """
 # pylint: enable=invalid-name
diff --git a/tests/unit/test_exceptions.py b/tests/unit/test_exceptions.py
index 10599457..e9709f26 100644
--- a/tests/unit/test_exceptions.py
+++ b/tests/unit/test_exceptions.py
@@ -102,6 +102,7 @@ def test_from_http_response_no_content():
 
 def test_from_http_response_text_content():
     response = make_response(b"message")
+    response.encoding = "UTF8"  # suppress charset_normalizer warning
 
     exception = exceptions.from_http_response(response)